Paul, price depends on your local market. Some places, used Genny's go for cheap, other places they are sky high. The grill you linked to is a Weber Genesis Silver A and it would have to be near flawless for me to even think about paying $175 for it.
If I were you, I'd be looking for a 3 burner Weber Genesis with or without a side burner. Reason being is that there often isn't much of a price difference and what's it going to hurt if there's an extra burner tube or a side burner ? There might come a time where one or the other might come in handy.
When picking up used Webers, I look at what the total cost would be. For a 3 burner with side burner (Silver/Gold C), pristine condition is worth about $250 to me (with tank). On a particular grill, each thing that I would have to replace lowers the price I am willing to pay. For example, new flavorizers would cost me about $45 or so from a guy named RCPlanebuyer, so if everything else was almost perfect, I'd pay $200. If I had to replace the grates as well, that would cost me about $60, dropping the offering price down to $140.
All of the above would apply to a 3 burner (Silver/Gold B), but the max starting price for me would be $200. If I were to pick up a 2 burner (Silver A), the most I'd pay would be about $150, but again, that's if everything is in great shape and won't need to be replaced within the next 3 or so years.
As for the grill I posted the link to, if nothing needed to be replaced, it's easily worth $200. That's not counting the included rotisserie or cover.
One other thing. Don't turn away a nice grill just because it might need some painting. Usually, the end caps are the main thing to be painted and you can hit those with a can of Rustoleum high heat grill spray paint. If you are good with a piece of cardboard, you wouldn't even have to mask it off.